Addition of plerixafor in poorly mobilized allogeneic stem cell donors

Peripheral blood stem cells (PBSCs) are the predominant graft source for adult allogeneic hematopoietic stem cell transplantation (HSCT). In poorly mobilized autologous donors, plerixafor improves collection outcomes. We examine plerixafor use in allogeneic donors who mobilize poorly with granulocyte colony-stimulating factor (G-CSF) in those who are healthy and those with pre-existing medical conditions, and determine the optimal threshold to add plerixafor.

We retrospectively examined all allogeneic PBSC collections from January 2013 to October 2020 at our center. Donors received G-CSF 10 mcg/kg daily for 4 days before undergoing apheresis collection on day 5. Plerixafor was added based on poor CD34+ cell collection yield after the first or second collection day.

Of the 1008 allogeneic donors, 41 (4.1%) received one dose of plerixafor in addition to G-CSF due to poor collection yield. After starting plerixafor there was a 0.75- to 7.74-fold (median 2.94) increase in CD34+ yield from the previous day. No donors with G-CSF-only mobilization who collected <2.0 × 10⁶ CD34+ cells/kg recipient weight on day one achieved the goal of ≥4.0 × 10⁶ CD34+ cells/kg recipient weight total over 2 days but 59.2% of donors who used rescue plerixafor did.

Donors both healthy and those with pre-existing disease responded well to plerixafor with minimal side effects. If the first-day collection yield is less than ~63% of the collection goal, addition of plerixafor may be necessary to reach the collection goal and limit the number of collection days in allogeneic donors.